Search Documents

This paper describes DRA?s involvement with the expansions at Tati Nickel, Phoenix Mine, that have taken an initial plant design of 3.6 Mtpa (originally built by Murray & Roberts), up to 5 Mtpa, and eventually 12 Mtpa capacity. Initially, the plant could not achieve the design name plate capacity for the first few years of operation, as a consequence of the notoriously hard and abrasive nickel ore affecting primarily the operation of the crusher circuit. In order to extend the life of mine, Tati? assessed and then redefined the mining plan, choosing to increase the Phoenix mine reserves to a lower cut-off grade. In order to increase nickel units produced, the concentrator had to therefore treat additional tonnage at lower head grades. Site investigations and field tests around the comminution circuits are outlined, indicated that the milling circuit could be increased to 650 tph, from the initial design of 470 tph, for a similar feed grade and recovery. A project was initiated to debottleneck the crusher circuit and achieve the new target throughput. (Project 5M). This was followed by a feasibility study of the impact of pre-concentration by DMS, which after promising laboratory tests, was followed up with the installation of a 200 tph ?demonstration? plant. The success of this demonstration plant provided the impetus to expand the supply to the 5 Mtpa mill from a large preconcentration stage. A gyratory crusher (one of the largest and most powerful) will receive ore directly from the open pit operation, feeding into a secondary-tertiary crushing plant followed by a modular DMS preparation circuit. Four large DMS processing modules have been installed to treat the tonnage, with high expected rejection levels. Finally a review of the DMS process capability on an ostensibly disseminated micro-gabbro nickel ore is given, which shows the remarkable impact that preconcentration can have on an operation, both in terms of profitability and a successful process ?expansion?. The performance of the DMS plant has significantly extended the life of mine, allowing the mine to significantly reduce mine cut-off grades and curb its previously selective mining practice.

Jan 1, 2009

By G. P. Schoonraad, J. E. Clay

Treatment of zinc silicates by the Waelz Process by J. E. CLAY (M.I.M.M.) (Visitor) and G. P. SCHOONRAAD. Pr. Eng.. B.Sc. Eng. (Rand) (Member) A review is given of the Waelz process. The chemistry of the process and the mechanism of crust formation (accretions) are briefly dealt with. The plant of Kiln Products Limited and its operation are described. The problems encountered and methods for their elimination are presented.

Jan 8, 1976

By J. W. van der Merwe

Technology is advancing at a rate that makes it extremely difficult for the mining industry to keep pace. Many advances occur within a given piece of technology and often this is missed by the disciplines that could have gained advantage by its implementation. Often this may have been simply an aspect of cost exceeding benefit. However, there are some technologies that potentially have such a far-reaching impact on the mining industry that the benefits simply outweigh the cost. The application of 3D laser scanning in the mining industry has the potential of taking the concept of 'Google maps?' underground. This presents an opportunity where the virtual world of underground can be traversed with relative ease and many aspects of measurements could be obtained without having to visit the working place again, potentially saving countless man-hours and still delivering precision work with significant savings in downtime, stoppages, and exposure to safety incidents. Anglo American Platinum maintains its competitive advantage though the review and application of appropriate technology. This paper describes the 3D laser scanning trial at one of Anglo American Platinum's new shafts, and goes on to show the benefits encountered through the application and the involvement of the various MRM disciplines.

Jan 1, 2013

By S. T. Camagu, J. Dutta Majumdar, S. L. Pityana

Laser surface alloying was used to develop copper and molybdenum aluminides by injecting premixed copper and molybdenum powder particles into a laser-generated melt pool on an aluminium substrate. Different laser processing parameters were used to produce the composite thin layers on the substrate material. The microstructure and phase constituents of the composite layer were studied by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) techniques. Experimental results show that the matrix structure of the metal matrix composite layer consists of ?-CuAl2and MoAl5. Surface hardness was increased by a factor of 3.

Jan 1, 2015

By D. R. Hack

The complexity of commercial mining software has gained rapidly over the past decade as hardware developments have surpassed software capabilities at a staggering rate. Software users, recognizing the limitations of off-the-shelf applications, have adapted embedded scripting languages. Custom programming has always had a vital role in mine computing innovations, yielding a dynamic research environment in industry and academia. Fields such as industrial minerals can benefit from customization of existing software, since the majority of mine planning software was designed for large metal mines. Different customization approaches utilizing embedded scripting languages are presented, with examples of sand and gravel applications in development. Following implementation by Surpac and development of the Surpac Command Language, Tcl has been widely applied. Mintec introduced Python, also extensible and portable amongst various operating systems, for use in their MineSight products. In early 2000, Gemcom introduced the use of Microsoft Visual Basic for Applications, widely used customization tools for a decade. Datamine implemented a flexible multi-language approach, with all program commands and processes available through the COM Server Interface. This extends customization from the existing macro language to scripting in HTML, JavaScript, or any language that supports COM.

Jan 1, 2003

By S. Parada, P. T. Jones, M. Guo, S. Smets

The corrosion behaviour of a high-quality rebonded magnesia-chromite refractory in contact with a vacuum oxygen decarburization (VOD) slag with high Al2O3content (15?20 mass per cent) is investigated under VOD process conditions by rotating finger tests in a vacuum induction furnace. The refractory degradation mechanisms are studied by the characterization of corroded microstructures using scanning electron microscopy, equipped with energy dispersive spectroscopy. The influence on the refractory wear of the process temperature and the Al2O3content in the slag is discussed. Keywords: corrosion, magnesia-chromite refractory, VOD slags, vacuum induction furnace

Jan 1, 2004

By L. Dison

This technical note is issued in two parts as follows. Part I, which appeared in the January issue of this Journal, after a brief introduction, discusses the value of patents and the law of patents, including patent applications and the exploitation of inventions. This is followed by some comments for the benefit of would-be inventors and potential users of patents. Part I focuses on the mining industry and then discusses views on patents that were quoted in Part I. The last section makes recommendations as to how inventors and users (including mining authorities) should handle patents.

Jan 1, 1992

By M. Bailey-McEwan

The application of refrigeration on deep South African gold mines is mostly achieved through the medium of chilled water which is produced in central installations either on surface or underground. The amount of refrigeration has been increasing rapidly over recent years, and the total installed capacity on all gold mines now exceeds 1000 MW(R), with annual running costs exceeding R100 million for electricity alone. Hence, there are strong incentives to design such installations for optimal cost-effectiveness. The duty required of these installations varies considerably, owing to daily and seasonal climatic changes and the varying nature of the water demand. It has long been recognized that a computer program to predict installation performance as a whole under any given conditions would be highly desirable. An interactive computer program, CHILLER, is described which enables the user to build an installation, consisting of any configuration of cooling towers, water storage reservoirs and packaged water chilling machines. Externally-dictated conditions such as the weather and chilled water demand must be specified, and all quantities under control of the installation, including internal water flow rates and compressor capacity regulators, must be set. The time-varying performance of the installation can then be simulated. Examples are given of the application of the program in the design of a new installation, and in evaluating the effect of any modifications to existing installations.

Jan 1, 1987

By P. G. Toledo, R. I. Jeldres, G. R. Quezada

Chile is the main producer of copper in the world and lately the mining industry has suffered challenges due to the lack of water in the north of the country, along with the new policies of not using fresh water for the industry. This has prompted the use of seawater as an alternative source for mining. Several studies have been driven due to this new scenario, which have shown that seawater can be beneficial, if certain ions are removed from the process. This is the Mg that generates precipitates at high pH, that have been shown to make mining operations difficult. In particular, thickening operations are impaired by the presence of Mg ions, where aggregate formation and sedimentation decreases substantially. Our studies suggest the competence of the precipitates in adhering to the polyacrylamide (HPAM) flocculant and not towards the surface of the quartz minerals. This motivates the present work to use molecular dynamics to study the adsorption of a HPAM molecule on quartz surfaces and the surfaces formed by Mg precipitates. The surfaces are immersed in a saline solution or seawater that includes the HPAM molecule. Results are obtained by measure the adsorption frequency and duration. We obtained that the HPAM molecules are preferably absorbed on the surfaces of magnesium hydroxide. This gives us a good agreement with what is observed experimentally and strengthens the premise of the competition of hydroxide with the flocculant. Keywords: Molecular dynamics, adsorption, tailing flocculation, magnesium removal

Jan 1, 2020

By N. D. Fernandes

Labour-intensive narrow reef stoping, as traditionally practised in South African gold and platinum mines, is almost unique in the modern first-world mechanized mining environment. Shortcomings of the system include the ever increasing cost of labour, a cap on achievable productivity and a poor safety record, particularly in the field of rock-related accidents. In the absence of sustainable alternative technologies, the South African mining industry has spent millions of rands improving the present system, focusing on improving workplace safety. This paper details the changes to stope support at Impala Platinum?s Rustenburg operations, and the impact on rock-related safety performance. Keywords Stope panel support, narrow reef stoping, improving workplace safety.

Jan 1, 2011

The Namakwa Sands heavy mineral deposit is located along the West Coast of South Africa and the mine is a world class producer of high quality zircon, ilmenite and rutile concentrates from essentially unconsolidated marine and aeolian sands of Cainozoic age. The objective of this study was to characterize rutile with respect to distribution, grain size, textures, colour and mineral chemistry within the Namakwa Sands orebody with the aim to explain its overall poor recovery. A representative suite of heavy mineral concentrates from various sections of the orebody and stages in the recovery circuit has been investigated microscopically and by means of SEM-EDS and LA-ICP-MS. The rutile grain size distribution displays a wide range and is directly related to its variable chemistry and consequently density. In placer deposits such as Namakwa Sands, mineral sorting is a function of hydraulic equivalence, and high density grains are smaller than the lighter grains when deposited under similar conditions. Grain size is also a function of sediment maturity, and the highly mature red aeolians and (RAS) component of the deposit has a coarser grain size than the less mature orange feldspathic marine sands (OFS). The above primary characteristics of rutile are responsible for the loss of the coarse-grained fraction during screening and, given the empirically determined relationship that increased substitution elements reduce conductivity, also during electrostatic separation. Provenance studies using geothermometry have shown that the heavy mineral suite has been sourced mainly by the proximal medium-to high-grade Namaqualand Metamorphic Complex. The positive relationship between substitution elements and temperature of formation explains their high concentration in rutile of this deposit. The heterogeneity of rutile, produced by the combination of a high temperature primary source and the typical marine-aeolian placer genesis is deposit specific and unfortunately not conducive to high recovery levels in the current Namakwa Sands beneficiation circuit.

Jan 1, 2010

By J. J. leR. Cilliers

ABSTRACT The recently introduced concept of negative taxation complicates estimation of the distributable profit of certain South African gold mines, and an assisted mine could operate at a working loss and yet produce an overall profit for distribution amongst its shareholders. A simple diagram is presented from which the approximate working profit or loss, taxation payable or tax credit received, and the distributable profit of an assisted mine can be estimated directly for any combination of the four main variable operational factors: tonnage milled, recovery grade, unit cost and capital expenditure. INTRODUCTION The effects on the working profits of South African Gold mines caused by changes in unit working costs, recovery grade, tonnage milled and capital expenditure are readily estimated. For normal tax- and lease-paying mines the distributable profit is related to the working profit and the latter is a commonly accepted comparative measure of the profitability of an operation. However, the recently introduced concept of State assistance in the form of negative taxation1, i.e. a tax credit, for mines with a life of less than eight years complicates such estimates. A requirement of State assistance is that an assisted mine must lower its normal pay limit by 16 to 20 per cent, and it will be possible for a mine to operate at a working loss and yet produce an overall profit for distribution amongst its shareholders. In the case of an assisted mine it is therefore necessary for management to judge the effects of changes in unit costs, grade, etc., in terms of distributable profit instead of working profit. This will require repeated calculation of tax to be paid or tax credits that will be received under the numerous possible combinations of the four main variable factors. However, with the aid of the diagram illustrated in Fig. 1, it is possible to assess at a glance the practical effect of these variables on the distributable profit of an operation not subject to tax on the normal formula, or small mine formula, with sufficient accuracy to decide whether a detailed analysis is required. USE OF THE DIAGRAM From the central point 'X' in Fig. 1, a range of tonnages milled per annum has been plotted along the north-bearing axis, a series of costs per ton milled in the northwestern quadrant, recovery grades in the northeastern quadrant, and capital expenditures in the southwestern quadrant. Starting from the tonnage milled per annum, a line is drawn east and west across the two northern quadrants up to the points where it reaches the desired cost- and grade-lines. From these points two north-south lines are drawn into the southern quadrants. A further line is drawn to the east from the point where the western north-south line crosses the desired capital expenditure. Distributable profit is read off in the southeastern quadrant where this line intersects the eastern north-south line. Every possible combination of

By A. Muwila

Hercules? is a low nickel austenitic stainless steel developed at Mintek that has a typical composition of 9 wt% Mn, 0.05 wt% C, 2wt% Ni, 0.25 wt% N and 16.5 wt% Cr. A more corrosion resistant version of Hercules? (Hercules? B) with 0.5 wt% Mo has also been developed. Potentiodynamic tests performed on Hercules? B in a 5wt% sulphuric acid solution showed it to have improved corrosion resistance comparable to that of AISI 304. The effect of a varying Mn content on the corrosion resistance of Hercules? B has also been investigated and the results discussed in this paper. From the corrosion test results, it is clear that decreasing the Mn content of Hercules? B increased the corrosion rate, while increasing it decreased the corrosion rate. Keywords: austenitic stainless steel, % ferrite, molybdenum, manganese, nitrogen, electrochemical corrosion tests, potentio-dynamic scans, microstructure, chemical analysis.

Jan 1, 2007

By H. L. Monro

The individual supplies of and demands for gold that make up the total supply/demand structure in any year, together with their individual price elasticities, are used to determine the effect of forward sales on the gold price.

Jan 1, 1992

By G. Coetzer, J. C. Davidtz

The substitution of functional groups in covalent trithiocarbonate collector molecules influences the selective and non-selective bonding of collector molecules to mineral surfaces, as well as flotation efficiency in a mixed sulphide ore. These effects were concluded to be related to the metal-sulphide solubility products and electron densities on the sulphur atoms in the collector

Jan 1, 1989

By Y. P. Shoupletsov

ABSTRACT. A retrospective analysis of some geomechanical classifications for rock masses is presented. It is shown that estimates of rock mass strength according to geomechanical classifications developed, e.g., for construction of tunnels and for ore mines can differ very much. Development of specifically oriented classifications for rock masses with certain geomechanical properties is required. ZUSAMMENFASSUNG. Es wurde eine retrospektive Analyse einiger geomechanoschen Klassifikationen von Gesteinsmassiven durchgefuhrt. Es idt aufgezeigt worden, dass die Bes-timmung der Festigkeit des Massivs nach geomechanischen Klassifikationen, die z.B. fur den Bau von Tunnelen und fur Erzbergwerke entwickelt wurden, sich um etliche Male unterscheiden kann. Es ist eine Entwicklung von spezialisierten Klassifikationen fur Gesteinsmassive mit bestimmten geomechanischen Eigenschaften erforderlich. RESUME. Il a ete fait l’analyse retrospective de certaines classifications geomecaniques des massifs de roche. Il a ete montre que les estimations de solidite du massif suivant les classifications geomecaniques etudiees, par exemple, pour la construction des tunnels et pour les puits de minerai peuvent differer en quelques fois. Il est donc necessaire d’etudier les classifications specialisees pour les massifs aux proprietes geomecaniques particulieres.

Jan 1, 2003

By W. C. Joughin

A risk evaluation model has been developed that enables the quantification of expected injuries and economic losses resulting from rockfalls associated with a support system in a given geotechnical environment, which is described in Part I (Joughin et al., 2011b). Part II presents the validation of the risk evaluation model. Underground mapping of joints and rockfalls was carried out to provide data for field calibration of the model. This survey was limited to small rockfalls, due to the relatively short period of mapping. Therefore the model was also correlated with rockfall and rockfall injury data collected by mine personnel. The analyses showed that the model provides a reasonable estimate of the expected frequency and size of rockfalls and the frequency of rockfall injuries, but further work is required to enhance the model. Three case studies are presented, which show the benefits of improved support systems from both economic and safety perspectives. This work has demonstrated that the risk evaluation model and the software developed are immediately useful, but further work is required to develop and improve the tools.

Jan 1, 2012

Contribution by W. Assibey-Bonsu I congratulate Mr N.O. Lotter on his paper. There are two main aspects of the paper on which I would like to comment. One aspect is his review of P. Gy's sampling theory under the heading 'Sampling the mill feed' (p. 153). The other aspect relates to his reference to one of our papers1 that was published in the Journal (p. 152). My comments on the former will be given elsewhere'. Authors' reply: Dr Assibey-Bonsu's contribution to the subject is appreciated.

Jan 1, 1996

By B. H. Sandelowsky

Prehistoric metal-working in South West Africa by B. H. SANDELOWSKY*, Ph.D. (Visitor) This paper describes a three-hundred year old metal-working site at Rehoboth, and makes a plea for information on such sites elsewhere in South West Africa so that they can be investigated. The technique of ore smelting that was used at Rehoboth appears to be different from that practised elsewhere by Bantu peoples before the modern era.

Jan 5, 1974

By M. C. Harris

Float-sink analysis has wide application in the coal laboratory. This paper evaluates the established methods used for the float-sink analysis of fine coal, and then describes a new method and apparatus that can be used for material down to a few micrometres in size. The method is rapid and accurate, and requires only a small amount of sample. The results presented show close agreement with the float-sink analyses obtained by the more classical technique using separating columns. The new centrifugal method reduces the time required for the analysis by a factor of ten.

Jan 1, 1986